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Unread 02-07-2004, 12:29 PM   #68
BillA
CoolingWorks Tech Guy
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Join Date: Dec 2000
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Quote:
Originally Posted by pHaestus
Bill a question about your heatpipe:

If you go low enough in power applied do you see a flat C/W vs power region? I'd expect that you'd hit a point where there isn't enough heat to cause a phase change in the pipe. Then if you keep boosting power over the heatpipe's working range far enough does it return back to that same flat line? Where you just add so much more heat into the system that the heatpipe doesn't work because the cold side is too hot?

I am visualizing a situation where at really low and really high power (temperatures completely outside the heatpipe's operating range) that you get performance that is pretty similar to just the heatsink alone, and that only within mfgr specs is there a big improvement by adding a heat pipe.

I have never personally used a heat pipe though so I could be way off base about how they supplement convective cooling...
I too would guess that at extremes, a heat pipe is a lump of copper,
and a 'good' plot would show the hysteresis curves;
but really at extremes

excess local heating will cause the 'vaporising area' to dry out, and that is the end of the heat pipe until it is cooled and re-condenses

not too sure I would agree with "supplement convective cooling", while convection is one of the mechanisms utilized, a 'heat pipe solution' would utilize the heat pipe as the primary transport mechanism
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